JSFiddle - React, Tailwind, and code Playground

by bradleytrager

HTML

<ul id="theList">
    <li>6</li>
    <li>3</li>
    <li>1</li>
    <li>4</li>
    <li>7</li>
    <li>5</li>
    <li>4</li>
    <li>2</li>
    <li>1</li>
    <li>8</li>
    <li>9</li>
</ul>

JavaScript

/*
Write an algorithm that will find the first duplicate in a list on the page.
For example we would return 4, for the list above.
*/